The invention relates to a detector for detection of ionizing radiation, to an apparatus for use in radiography and to a method for detecting ionizing radiation.
A drawback with conventional gaseous parallel plate avalanche chambers is that the electrical field between the electrodes, i.e. the voltage applied between the electrodes, needed for efficient operation of the instrument is close to the limit where sparks are produced which could harm the detector.
A main object of the invention is to provide an improved detector for detection of ionizing radiation, which employs avalanche amplification, and ensures stronger focusing effect than in conventional designs, and which can be manufactured in a simple and cost effective way. The stronger focusing effect will render the streamer formation more difficult compared to prior art designs.
This and other objects are attained by a detector for detection of ionizing radiation, comprising, a chamber filled with an ionizable medium, at least one first electrode arrangement provided in said chamber where said at least one first electrode arrangement includes an electron avalanche amplification unit, said electron avalanche amplification unit including at least one avalanche cathode and at least one avalanche anode between which a voltage is to be applied for creation of an electric field for avalanche amplification, and at least one arrangement of read-out elements for detection of electron avalanches, wherein said at least one avalanche cathode has at least one hole or opening, wherein an area of said at least one hole or opening in the avalanche cathode is bigger than an area of at least one associated anode as seen from above and where said at least one anode is centered with respect to said at least one hole or opening in the avalanche cathode.
The detector also can operate at high X-ray fluxes without performance degradation and has a long lifetime.
The detector of claim 1 also achieves effective detection of any kind of radiation, including electromagnetic radiation as well as incident particles, including elementary particles.
It is also an object of the invention to provide an apparatus for use in radiography comprising said detector for detection of ionizing radiation, which employs avalanche amplification, provides well-defined avalanches, and can be manufactured in a simple and cost effective way.
This and other objects are attained by an apparatus for use in radiography, comprising an X-ray source, and a detector for detection of ionizing radiation, comprising a chamber filled with an ionizable medium, at least one first electrode arrangement provided in said chamber where said at least one first electrode arrangement includes an electron avalanche amplification unit, said electron avalanche amplification unit including at least one avalanche cathode and at least one avalanche anode between which a voltage is to be applied for creation of an electric field for avalanche amplification, and at least one arrangement of read-out elements for detection of electron avalanches, wherein said at least one avalanche cathode has at least one hole or opening, wherein an area of said at least one hole or opening in the avalanche cathode is bigger than an area of at least one associated anode as seen from above and where said at least one anode is centered with respect to said at least one hole or opening in the avalanche cathode.
The apparatus for use in radiography, may also include a simple and inexpensive detector that can operate with high X-ray detection efficiency and with good energy resolution for X-rays.
The apparatus for use in radiography, may also include a detector which can operate at high X-ray fluxes without a performance degradation and has a long lifetime.
It is also an object of the invention to provide a method for detection of ionizing radiation, which employs avalanche amplification, provides well-defined avalanches and focusing of the electrons by means of at least one focusing electrode, and can be implemented in a simple and cost effective way.
This and other objects are attained by a method for detecting ionizing radiation, wherein the radiation interacts with atoms in a volume filled with an ionizable medium, for creation of released electrons, said method comprising forming in each of at least one region, including at least one avalanche cathode and at least one avalanche anode, a concentrated electric field for causing electron avalanches, and detecting the electron avalanches with readout elements, by focusing the electrons with at least one anode, having a smaller area than associated holes or openings in the at least one avalanche cathode and where the area of the at least one anode is centered with respect to the associated holes or openings in the at least one cathode.
The method can be used at high X-ray fluxes.